Cannot manually tilt Mercury 20 OB, Tilt and Trim is locked in down position, what I found...

This is a old Mercury 20 Hp outboard that is mounted or hung off the back of a 17' fishing boat and hooked up to a binicle and steering wheel. There is no tiller arm on this model. The issue is, the motor is locked down which is the Tilt and Trim. It is not a hydraulic set up but a manual tilt and trim. By design, the binicle should be in forward gear which unlocks the tilt and trim locking device. The boat also has no gear, forward or reverse when the binicle is placed in fwd or reverse. I have never worked on a motor like this so I recorded what I have found and how I fixed it. It's a very simple part called a "socket". Part# is in the video.
Products used in this video I had bought with my own money. There is no promotion for them.

[@grayleym]

What is the name and number of the part please, so I can order it. Thanks

[@bigguydiy2184]

I showed the part number in the video. Mercury part#817428 Socket